A secondary cell after long use has an emf of 1.9V and large internal resistance of 380 `Omega`.
What maximum current can be drawn from the cell? Could the cell drive the starting motor of a car?

Explanation

Given emf of each cell= 2.0V
Total emf of six cells `= 2xx 6 = 12V`
Total internal resistance= `6 xx 0.015Omega = 0.090Omega`
Load resistance = `8.5Omega`
Given E = 1.9V, r = 380`Omega`
`I_("max")=E/r=(1.9)/(380)A=5xx10^(3)A`
The current required to start the motor is about `2 xx 10^(4)` times the maximum current of `5xx10^(-3)A`. Hence the cell cannot be used to start the car.